Lung Cancer

Background and Epidemiology

  • Most common cause of death from cancer worldwide (18% of all cancer deaths)
  • Prognosis is very poor with 1 year survival at 30% and 5 year survival only 6-8%
  • Although still more common in men, the incidence in men is falling.  In contrast, the incidence in women is rising (reflects smoking activity)

Classification

  • Small cell lung cancer (15-20%)
    • Arise from Kulchitsky cells (APUD/Endocrine cells)
    • Often secrete hormone/neurotransmitter like chemicals with can cause extrarespiratory symptoms and can also act to increase tumour growth
    • They are rapidly growing and highly malignant (almost always inoperable but can respond to chemotherapy- however, the prognosis is poor)
  • Non-Small cell lung cancers (remainder)
    • Squamous cell carcinomas (40-45% of NSCLCs)
      • Usually presents as an obstructive lesion of the bronchus causing infection/lobe collapse
      • Local spread is common but metastatic spread is often late (however, still common)
      • Often causes hypocalcaemia (bone destruction/PTH analogues)
      • Often appears as a cavitating lesion on imaging
    • Adenocarcinoma (40% of NSCLCs)
      • Arises from mucus cells
      • associated with asbestos exposure and is also more common in non-smokers than other types
      • Commonly causes pleural effusions
    • Large cell tumours (10%)
      • Poorly differentiated cells
      • Metastasise early and poor prognosis
    • Others e.g. carcinoid tumours and bronchoalveolar cell tumours

Aetiology/Risk Factors

  • SMOKING (mainly tobacco)
    • Responsible in >90% and proportionately so (i.e. more smoking- more risk; if you stop smoking, your risk declines)
    • COPD (also likely secondary to smoking)
  • Age
  • Industrial dust diseases / occupational exposures to e.g. asbestos, iron oxides, chromium, radiation
  • Family/personal history of lung cancer or head/neck cancer

Presentation

  • Cough
    • Often dry although can be productive of purulent sputum if there is secondary infection
    • For a smoker with chronic cough/COPD/bronchiectasis, any change in cough should raise suspicion
  • Haemoptysis
    • All haemoptysis in smokers should be investigated fully for bronchial (lung) cancer
  • Bronchial obstruction
    • Can be
      • Complete
        • Causes lobe collapse- breathlessness, mediastinal displacement, dullness to percussion and reduced breath sounds over the affected area
      • Partial
        • Often causes breathlessness with a monophonic, unilateral wheeze.  However, more commonly predisposes to a lobar pneumonia
    • Pneumonia which recurs in the same area or responds slowly to treatment (esp in smokers) suggests possible cancer
  • Shortness of breath (caused by collapse, pneumonia, pleural effusion)
  • Pain/nerve entrapment
    • Pleural chest pain is often a symptom of malignant invasion into the pleura or secondary to infection
    • Carcinoma of the lung apex may cause Horner’s syndrome
      • Ipsilateral partial ptosis, enophthalmos, miosis and hypohidrosis of the face
      • due to invasion of the sympathetic chain
      • may also be associated with Pancoast’s syndrome (Pancoast tumour) which can present with pain in the inner arm +/- small muscle wasting of the hand
  • Dysphagia
  • Dysphonia (and a bovine cough- lacking explosive character)- suggests laryngeal nerve involvement
  • Lymphadenopathy
  • Finger clubbing
  • Systemic symptoms
    • weight loss, night sweats, fever, anorexia
    • jaundice
    • change in personality/confusion
    • bone pain

Investigations

  • Imaging
    • CXR
      • Unilateral hilar enlargement
        • Central tumour with hilar glandular involvement
      • Peripheral pulmonary opacity
        • Usually irregular but well circumscribed and may contain cavitating regions
      • Lung, lobe or segmental collapse
      • Pleural effusion (may indicate invasion into the pleural space)
      • Broadening of mediastinum, enlarged cardiac shadow, elevation of a hemidiaphragm
        • Paratracheal lymphadenopathy may cause the widening
        • A malignant pericardial effusion will enlarge the cardiac shadow
      • Malignant rib destruction
    • CT (usually + PET) is best to clarify and stage the cancer
  • Bronchoscopy and biopsy
    • If unfit- sputum cytology
  • Bloods
    • FBC- lung cancer (esp SCLC) can spread to bone marrow and cause a pancytopenia (particularly neutropenia)
      • Other features include anaemia, thrombocytosis
    • LFTs may be abnormal if metastatic disease present
    • U&Es
      • Acute kidney injury may be present in association with pneumonia
      • Calcium may be high

Management

  • Based on individual patient.  Options are
    • Surgery
    • Radiotherapy
    • Chemotherapy

When to refer

  • Immediate
    • Signs of SVC obstruction e.g. facial/neck swelling; stridor
  • Urgent
    • Persistent haemoptysis (in patients >40 with a smoking history (current or ex))
    • CXR suggestive of Lung ca e.g. mass, collapse, pleural effusion or slowly resolving consolidation
    • Normal CXR but high suspicion of cancer
    • Hx of asbestos exposure and recent onset chest pain, SOB or unexplained systemic symptoms
  • Refer urgently for CXR
    • Haemoptysis
    • Unexplained or persistent
      • Chest/shoulder pain
      • Dyspnoea
      • Weight loss
      • Chest signs
      • Hoarseness
      • Finger clubbing
      • Cervical/supraclavicular lymphadenopathy
      • Cough
      • Features suggestive of metastases
      • Changes in underlying chronic respiratory symptoms
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